The invention relates to a jointing unit for jointing seams, particularly seams supplying migratable material which may escape from between the opposed jointing zones or flange faces. Such material may be jointing material formed directly by the jointing flanges, i.e. solids such as particles capable of escaping laterally from between the jointing faces.
In the production of fusion or welded joints on components of plastics or the like the energy needed to melt the jointing material may be achieved by causing the jointing faces to be rubbed against each other by oscillation until they weld together. In this arrangement the jointing faces are rubbed together at a speed of 500 to 1000 mm per second for 2 to 8 secs at an oscillation frequency of 85 to 250 Hz and at an oscillation amplitude of 0.5 to 2 mm. The jointing faces are initially rubbed off by a depth of approx. 0.5 to 1 mm before then being melted off. Thereby the jointing faces are correspondingly approached toward each other.
Before the melting temperature is attained attrition particles are generated during the solid friction phase. These particles are required to remain between the flange faces. If the two components or dishes having annularly uninterrupted jointing flanges, flange faces or jointing faces are joined together by the seam to form a tank or container the cited attrition material must not gain access to the interior of the tank irrespective of how long the tank is in operation. Otherwise the contents of the tank would be soiled.
This applies especially to automotive fuel tanks whose communicating conduits from the tank to the combustion chamber would be choked up by such particles. Although the interior of the tank could be cleaned out after the joint has been made, this is, however, extremely complicated and hardly achievable with full success. Even in the case of a concealed seam there is no absolute guarantee that fine to very fine solids particles are not expelled from between the coverings of the flange faces and gain access to the large faces of the walls interconnected by their flanges.
An object is to provide a jointing unit which avoids the disadvantages of known configurations or of the aforementioned kind. Another object is to prevent on one or both outer sides of the sealing seam the escape of the cited material from between the flange faces. A still further object is, that the jointing flanges, particularly the flange faces, are simple in structure and handling.
According to the invention means are provided to prevent migration of most of the cited material or every material towards at least one side out of the jointing gap between the flange faces. Such means may comprise one or more chambers for receiving the material between the flange faces or at least one seal for preventing coming forth of the material.
This seal is preferably a labyrinth seal. The sealing members of the two flanges do not come into contact with each other or, at the most, without any significant pressing. They do not rub against each other to such an extent that attrition materializes. The narrowest gaps of the seal may be at least 0.2 or 0.4 mm. The associated gap planes are parallel to the jointing faces and thus to the direction of vibration. The flanks of the sealing members directly mutually opposed remain out of contact during the vibration or come into contact but with no significant pressure.
It is particularly expedient when the chamber directly adjoining the jointing faces is larger than the next chamber or the one more remote from the jointing faces which may adjoin the larger chamber via a sealing point. The width of the larger chamber as measured parallel to the vibration motion is sufficiently large so that the associated side faces remain spaced from each other even in closest approximation during vibration. Thus space remains for receiving the material even with the most constricted chamber. Accordingly, the material is not expelled from this chamber into the next chamber or only in negligable amounts. When a transfer of material into the next chamber occurs, it remains captured there just the same as in the larger chamber during all the time the welded item is in use.
Due to the sealing points the stored medium is unable to be flushed out of the side joint gaps of the seam. The retention or damming gap or all damming gaps is/are narrower than the jointing faces. In cross-section the jointing gap may form at each outside a narrow sealing gap. Between the sealing gap and the jointing faces at least two or three chambers and at least one or two sealing gaps are provided which are expediently displaced transversely to each other and/or to the jointing faces.
It is particularly expedient when the sealing gap is narrower than the narrowest jointing face or seam. The sealing gap can then be bounded by a web or a rib, the thickness of which is max. 2 or 1 mm. As a result the web may also pivot about its root and execute resilient tilt motions, e.g. give place to the material on a constriction of the chamber and thus adapt the minimum chamber size to the chamber contents without attrition generating at the web.
The chambers which are closed or open only in the vicinity of the sealing gaps are configured to be not symmetrical relative to the center plane. This plane of the jointing faces is perpendicular to the jointing faces. Particularly between the outside of the jointing gap to be protected from emission and the jointing faces more or larger chambers or more sealing gaps may be provided than at the other side.